Verapamil, a calcium channel blocking agent, has been shown to have beneficial hemodynamic effects in patients with hypertrophic cardiomyopathy. To assess whether other drugs of this type hve similar effects, nifedipine was administered buccally in the Catheterization Laboratory to patients with this disorder. Although nifedipine appeared to decrease left ventricular outflow obstruction, its lack of effect on left ventricular systolic pressure and early diastolic filling raises questions as to whether it will be as effective as verapamil.